A massive chunk of ice calves from the face of the Perito Moreno Glacier in Parque Nacional Los Glaciares, near El Calafate, Argentina. The southern Patagonian ice field (Campo de Hielo Patagonico Sur) is the third largest concentration of fresh water in the world. The Perito Moreno is also one the only advancing glaciers left on Earth, creeping forward at a pace of around 2-3 meters per day and attracting hoards of tourists every year.